This invention relates to invert emulsions of improved extreme pressure (E.P.) properties, and more particularly to those used as fire-resistant lubricants and as fire-resistant hydraulic fluids.
Stable water-in-oil invert emulsions for use as lubricants and as fire-resistant hydraulic fluids are known from the prior art; as for example exemplified by U.S. Pat. No. 3,269,946 -- Wiese. Also, it is known to sulfurize polyisobutenyl succinic anhydride in order to obtain improved thermal stability; for example as exemplified by U.S. Pat. No. 3,664,955 -- Panzer. Other U.S. Patents illustrative of the prior art are 2,965,574 -- Tierney; 3,131,150 -- Stuart; 3,172,892 -- LeSuer; and 2,932,614 -- Lynch.
The primary use of invert water-in-oil emulsions has been as fire-resistant lubricating oils, and hydraulic fluids, for use in applications where the hazard of fire was significant. While the invert emulsions substantially reduced the risk of fire from oil or fluid leaks in hazardous applications, such emulsions are not particularly noted for their extreme pressure or anti-wear characteristics and properties.
It remained for the present applicants to provide a stable invert emulsion which also had improved extreme pressure and anti-wear properties.